X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 12 Aug 2010 08:20:16 -0400 Message-ID: X-Original-Return-Path: Received: from n20.bullet.mail.mud.yahoo.com ([68.142.206.147] verified) by logan.com (CommuniGate Pro SMTP 5.3.8) with SMTP id 4427586 for lml@lancaironline.net; Wed, 11 Aug 2010 23:45:55 -0400 Received-SPF: none receiver=logan.com; client-ip=68.142.206.147; envelope-from=mcmess1919@yahoo.com Received: from [68.142.200.226] by n20.bullet.mail.mud.yahoo.com with NNFMP; 12 Aug 2010 03:45:16 -0000 Received: from [68.142.201.242] by t7.bullet.mud.yahoo.com with NNFMP; 12 Aug 2010 03:45:19 -0000 Received: from [127.0.0.1] by omp403.mail.mud.yahoo.com with NNFMP; 12 Aug 2010 03:45:19 -0000 X-Yahoo-Newman-Id: 870402.5347.bm@omp403.mail.mud.yahoo.com Received: (qmail 41039 invoked from network); 12 Aug 2010 03:45:19 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=DKIM-Signature:Received:X-Yahoo-SMTP:X-YMail-OSG:X-Yahoo-Newman-Property:From:To:Subject:Date:Message-ID:MIME-Version:Content-Type:X-Mailer:Thread-Index:Content-Language; b=d/TnDRBJHYk82Q3zJwFtpoOoYASNeWkMYUVmEqwE7iHTm181sMjubj4mtG0yKx0QYXnlyO31v5qqQttPpcjAlUgxYoPXGflRodFiGPICMGa0BxvQMjPRIs8ziwJk5eH6aioK3vVPYrXaYDp12s7i49D0s9jXoXO69LfYygM1uRg= ; Received: from ClaudettePC (mcmess1919@67.187.169.61 with login) by smtp115.plus.mail.sp1.yahoo.com with SMTP; 11 Aug 2010 20:45:19 -0700 PDT X-Yahoo-SMTP: rK4i7HqswBC7mDE8.sOiWQeO4CeReXc- X-YMail-OSG: ITrEQbQVM1lPGymyuguEmlJreZNFJ6Iv_22FRa_ekn1Zi1N Z9RwpqsgPuqbCdRLayRYBdiPtzjfVLgfMVdIx_9yCK6f6LNTfucvHr5iw0ie xWbZlr8gaoDgyB3h8KBME.mKa9HEX3D4pnsfcpxesEnzHpkj9wwgIGyLwzaE dS5MhQgf.n9sRD2qAXp3oqvpu9YGAsMveCRk4biZaK7Qi.A.KIKWzmkbBtEe txEBpDesCS3XWsL_RFei_UnIl3t1cZQOOCeFOWsuETXhBSS0- X-Yahoo-Newman-Property: ymail-3 From: "Steve Colwell" X-Original-To: "'Lancair Mailing List'" Subject: fuel pressures at altitude? X-Original-Date: Wed, 11 Aug 2010 20:45:20 -0700 X-Original-Message-ID: <005701cb39d0$c9852c80$5c8f8580$@com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0058_01CB3996.1D265480" X-Mailer: Microsoft Office Outlook 12.0 Thread-Index: AcshJBT5d2MlifRyRKe8OBp2AFGtNwAWztWQAACUDRAAYT6XMAWtDRwg Content-Language: en-us This is a multipart message in MIME format. ------=_NextPart_000_0058_01CB3996.1D265480 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Russell, You may recall I had a fuel problem just prior to OSH this year (see below). I did some testing, inspection and cleaning before the next flight and got the opinions of several experts. My conclusions are warm fuel and higher ambient temps increase the likelihood of Fuel Vaporization in the system. Higher density altitude is also a significant factor. I managed to get away with not using the Low Boost Pump at some high cruising altitudes for a couple of hundred hours. Reasons to use Low Boost: On Takeoff, if the engine driven pump fails you are covered. Climbing out, fuel pressure will be stable and allow accurate leaning. At cruise, density altitude will not have a detrimental effect on fuel pressure. At Airventure, I spoke with several Lancair pilots, Continental and a Cirrus Test Pilot with over 8 years experience, all seemed to think this procedure is a good idea. If it means buying a Boost Pump sooner rather than later, I'm OK with that. Steve Colwell Legacy IO-550 On climb out to 14,500' yesterday I was having trouble leaning to 1300 degrees. The mixture knob was extra sensitive so I favored the rich side. I had just topped off with 40 gal. from an above ground tank that was probably around 80 to 85 degrees. Low boost was used from takeoff to about 1500' agl., RPM was reduced to 2500 and leaning began. Normally, maintaining 1300 degrees on the hottest cyl. in the climb (per The Advanced Pilot Course) is easy. (On the previous flight to 15,500' for 2.5 hours I noticed it did not lean normally but I was able to go LOP and it held the fuel flow @ 9.8 gph. No fuel had been added and temp on the ground was about 70 degrees.) When we reached 14,500', we accelerated in level off, reduced RPM to 2300 and started to ease the mixture knob back to go Lean of Peak. At 16.5 gal. per hr., slowly turning the Vernier about 1/8" as normal, fuel flow jumped to 9 gph. with the engine faltering. I tried this twice before concluding "this ain't right". I wish I had thought to use Low Boost or to check Fuel Pressure, but I didn't. We were over the Sierras and headed for the nearest airport but maintained altitude and finally circled down over Placerville, CA. I did not mess with the mixture on descent thinking a running engine was the best option. The control cable, bracket, arm and movement on the mixture are OK. Testing for leaks, I had the mixture in idle cut off, throttle open full. With Low Boost for about 20 seconds, no leaks. Steve Colwell 916 505-6099 Legacy IO-550N mostly stock, no ram air or injector mods., 225 hours tt. I'm a little confused over your use (or non-use) of the Electric Boost Pump at altitude? Try turning it on LO at 5,000 feet, and HI at 10,000. That's SOP for the turbos. The boost pump is your friend! On hot days, with hot fuel, you may need the boost pump for an hour or more at altitude. Sounds to me like simple vaporization. Best... John Deakin Advanced Pilot Seminars ------=_NextPart_000_0058_01CB3996.1D265480 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Russell,

 

You may recall I had a fuel problem just prior to OSH = this year (see below).  I did some testing, inspection and cleaning before = the next flight and got the opinions of several experts.

 

My conclusions are warm fuel and higher ambient temps = increase the likelihood of Fuel Vaporization in the system.  Higher density altitude is also a significant factor.  I managed to get away with = not using the Low Boost Pump at some high cruising altitudes for a couple of = hundred hours. 

 

Reasons to use Low Boost:

On Takeoff, if the engine driven pump fails you are = covered.

Climbing out, fuel pressure will be stable and allow = accurate leaning.

At cruise, density altitude will not have a detrimental = effect on fuel pressure.

 

At Airventure, I spoke with several Lancair pilots, = Continental and a Cirrus Test Pilot with over 8 years experience, all seemed to = think this procedure is a good idea.  If it means buying a Boost Pump sooner rather than = later, I’m OK with that.

 

Steve Colwell   Legacy  = IO-550

 

 

 

 

On climb out to 14,500’ yesterday I was = having trouble leaning to 1300 degrees.   The mixture knob was extra = sensitive so I favored the rich side.   I had just topped off with 40 gal. = from an above ground tank that was probably around 80 to 85 degrees.  =  Low boost was used from takeoff to about 1500’ agl.,  RPM was = reduced to 2500 and leaning began.   Normally, maintaining 1300 degrees = on the hottest cyl. in the climb (per The Advanced Pilot Course) is easy.  =  

 

(On the previous flight to 15,500’ for 2.5 = hours I noticed it did not lean normally but I was able to go LOP and it held = the fuel flow @ 9.8 gph.  No fuel had been added and temp on the ground was = about 70 degrees.)

 

When we reached 14,500’, we accelerated in = level off, reduced RPM to 2300 and started to ease the mixture knob back to go Lean = of Peak.  At 16.5 gal. per hr., slowly turning the Vernier about = 1/8” as normal, fuel flow jumped to 9 gph. with the engine faltering.  I = tried this twice before concluding “this ain’t right”.   I wish I had thought to use Low Boost or to check Fuel Pressure, = but I didn’t.  We were over the Sierras and headed for the nearest = airport but maintained altitude and finally circled down over Placerville, CA.   I did not mess with the mixture on descent thinking a = running engine was the best option. 

 

The control cable, bracket, arm and movement on the = mixture are OK.  Testing for leaks, I had the mixture in idle cut off, = throttle open full.   With Low Boost for about 20 seconds, no = leaks. 

 

 

Steve Colwell   916 = 505-6099    Legacy IO-550N mostly stock, no ram air or injector mods., 225 hours = tt.

 

I'm a little confused over your use (or non-use) of the Electric Boost Pump at = altitude?

Try turning it on LO at 5,000 feet, and HI at 10,000.  That's SOP = for the turbos.  The boost pump is your friend!  On hot days, with hot = fuel, you may need the boost pump for an hour or more at altitude.

Sounds to me like simple vaporization.

Best...
John Deakin
Advanced Pilot Seminars

 

 

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